Thionyl Chloride → 1-(Benzo[b]thiophen-3-yl)-3-chloropropan-2-one

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Reaction Steps

The procedure described above for the synthesis of 1-chloro-3-(thiophen-2-yl)propan-2-one was followed. To prepare the acid chloride, 2-(benzo[b]thiophen-3-yl)acetic acid (1.00 g, 5.20 mmol) was added to 6 mL thionyl chloride in a 25 mL round-bottomed flask. The mixture was stirred overnight at room temperature, and the thionyl chloride then removed in vacuo and the residue azeotroped twice with toluene. The acid chloride was then reacted with diazomethane and HCl. The crude product was purified by flash chromatography over silica gel (2-30% ethyl acetate in hexanes) to give pure material (0.661 g, 56% yield): 1H NMR (400 MHz, CDCl3) δ 4.12 (s, 2H) 4.14 (d, J=1.0 Hz, 2H) 7.36-7.44 (m, 3H) 7.67-7.71 (m, 1H) 7.87-7.90 (m, 1H).

Provenance & Evidence